BDD Minimization Using Graph Parameter Permutation

The size of a Reduced Ordered Binary Decision Diagram (ROBDD) is directly influenced by the variables ordering technique used to build the ROBDD. Therefore various variables ordering techniques have been proposed to minimize the size of BDDs. Unfortunately there is no unique method that can be used to obtain the least number of nodes for all BDDs. In this paper we propose two new methods based on permutation of various graph parameters. The first method uses the total number of nodes, the number of paths, the sum of shortest paths between inputs, and the maximum number of nodes among all paths. The second method is an extension of the first method using the shortest path between each input. The experimental results show the effectiveness of our proposed graph parameter permutation methods.